The invention relates to digital tape drive storage devices, and in particular, to a method for preventing a reverse connection between a takeup leader and a tape cartridge leader in a single reel tape drive.
Digital data is stored on tape drives utilizing a variety of designs, but in all cases, magnetic tape media is wound between a pair of tape reels as data is transferred to or from the tape media. In the art of data storage, the physical space required to store data is an important concern. To conserve space, tape drives often use a single reel tape cartridge design, which utilizes a supply reel located within a removable tape cartridge and a takeup reel located within the tape drive.
After the tape cartridge is inserted into the tape drive, the tape media must be loaded into the tape drive. The loading operation includes connecting the tape media to the takeup reel and winding the tape media to a start point or read position. Various methods have been employed to make this connection. FIG. 1 illustrates one such method wherein the tape media connects to the takeup reel via a buckle 100 between a tape cartridge leader 101 and a takeup leader 103. In this configuration, the tape cartridge leader 101 terminates the tape media at one end. The tape cartridge leader 101 is a strong flexible plastic strip containing an ovular aperture 102 configured to mate with the takeup leader 103. The takeup leader 103 is a similar strong flexible plastic strip attached at one end to the takeup reel. The opposing end includes a stem 104 and a tab 105 designed to buckle with the ovular aperture 102 on the tape cartridge leader 101. After the takeup leader 103 and the tape cartridge leader 101 are buckled, they are wound through a tape path past the tape head until the beginning of the tape media is in the read position relative to the tape head. Similarly, an unloading operation includes unwinding the takeup leader 103 and tape cartridge leader 101 back past the tape head and unbuckling the leaders so that the tape cartridge may be ejected from the tape drive.
Unfortunately, connection failures that cause the tape drive to malfunction can occur during the loading of the tape cartridge. Connection failures occur in different forms. One form of connection failure is a complete miss between the takeup leader 103 and the tape cartridge leader 101. When a complete miss failure occurs, the takeup leader 103 is pulled into the tape drive by the takeup reel during winding and cannot be pushed back into position for loading of subsequent tape cartridges. The tape drive is rendered inoperable and must be removed from its"" enclosure for service. This problem is particularly acute in library applications, where the insertion of a tape cartridge with a broken tape cartridge leader into successive tape drives may render the drives useless until the entire system is brought down. In addition, because the takeup leader 103 tends to wear out with use, the problem is most common in high duty cycle applications where it potentially does the most damage.
One solution to the problem of a missed connection rendering a tape drive inoperable is described in U.S. patent application 09/293,585. U.S. patent application 09/293,585 describes a sensing assembly that performs a buckle integrity test to detect missed connections. If a missed connection is detected the takeup leader 103 is automatically reset to the unloaded position and the tape cartridge is ejected. The sensing assembly comprises a microprocessor and at least one position sensor that detects movements in the tape drive consistent with either a proper connection or missed connection.
It is a problem following a missed connection to reset the takeup leader 103 to the unloaded position before the tape cartridge is ejected. The target area for the unloaded position is relatively small and the exact position of the stem 104 and tab 105 varies depending on factors such as wear and tape drive tolerances. One specific problem occurring during the reset operation is illustrated by FIG. 2 and is known in the art as a xe2x80x9creverse buckle.xe2x80x9d During a reverse buckle situation, the stem 104 and tab 105 of the takeup leader 103 are returned to the front side of the aperture 102 in the tape cartridge leader 101 and form a reverse buckle 200 with the tape cartridge leader 101. The reverse buckle 200 will not detach when the tape cartridge is ejected from the tape drive causing the tape cartridge to become stuck in the tape drive. If a user forces the tape cartridge out of the tape drive, the tape media and/or the tape drive can be damaged. As with the missed connection where the takeup leader 103 is drawn into the tape drive, the tape drive is rendered inoperable and must be removed from its"" enclosure for service.
Unfortunately, the problem of resetting the takeup leader 103 before ejecting the tape cartridge is not easily solved without redesigning the entire tape drive. The takeup leader reset operation is mechanically tied to the tape cartridge eject operation so that the tape cartridge cannot be ejected unless the reset operation is completed. Therefore, a need exists in the art for a simple low cost method of ejecting the tape cartridge prior to resetting the takeup leader.
The present invention overcomes the problems outlined above and advances the art by providing an inexpensive method for ejecting the tape cartridge from the tape drive prior to resetting the takeup leader to the unloaded position. A first advantage of the present invention is that the method prevents the possibility of a reverse connection failure by ejecting the tape cartridge before resetting the takeup leader to the unloaded position. A second advantage of the present invention is that the method provides a low cost solution without redesigning the tape drive.
The method comprises detecting a missed connection between the takeup leader and the tape cartridge leader following a failed load operation. The load operation includes loading the tape cartridge into the tape drive, connecting the takeup leader and tape cartridge leader, and winding the tape media to the read position. In response to detecting the missed connection, a torque is applied to the takeup leader to retain it in a loaded position away from the tape cartridge leader while the tape cartridge is ejected from the tape drive. In response to ejecting the tape cartridge from the tape drive, the takeup leader is reset to the unloaded position for a subsequent loading operation.